[Refractory acquired hemophilia A in which factor VIII inhibitor was not detected at onset and thereafter deteriorated after total hip replacement arthroplasty].

A 58-year-old man was admitted to a general hospital to undergo total hip replacement arthroplasty for idiopathic osteonecrosis of the right femoral head. Pre-operative screening examination demonstrated isolated prolonged aPTT. Factor VIII (FVIII) activity was mildly decreased but there was no detectable FVIII inhibitor, so he was diagnosed as having congenital hemophilia. Surgery was performed safely with administration of FVIII preparation but 33 days postoperatively bleeding from the right hip joint appeared. It was not controllable with FVIII preparation and he was therefore admitted to our hospital.Laboratory examination at admission demonstrated prolonged aPTT (111.1 sec), reduced FVIII activity (3.0%), and the presence of FVIII inhibitor (17.0 B.U./ml). He was diagnosed with acquired hemophilia and administered Factor IX complex concentrates, prednisolone and cyclophosphamide. However, these treatments had only a temporary effect. Rituximab was administered every week and his condition soon improved. This case suggests that acquired hemophilia, in which there was no detectable FVIII inhibitor, may change to refractory disease after surgery. As a result, surgeons should pay careful attention to the preoperative presence of any mild coagulation abnormalities.